The invention relates to a rolling bearing device with a sensor having raceway members, rolling elements, and a sensor unit, and particularly, to a hub unit having a sensor unit.
Conventionally, as a rolling bearing device with a sensor, there is a hub unit described in Japanese Unexamined Patent Application Publication No. 2001-21577.
This hub unit includes a rotating raceway ring, a fixed raceway ring, and one displacement sensor, and the displacement sensor is provided in the fixed raceway ring. Specifically, an outer peripheral surface of the fixed raceway ring has a hole that extends radially, and the displacement sensor is inserted into the hole. A detection surface of the displacement sensor is directed to an outer peripheral surface of the rotating raceway ring.
The displacement sensor detects a gap between the rotating raceway ring and the fixed raceway ring that changes depending on any displacement of the outer peripheral surface of the rotating raceway ring to be generated when a load acts on a wheel of a vehicle (specifically, an electric signal that changes in response to this gap). The hub unit calculates a vertical load that acts on the wheel on the basis of a gap detected by the displacement sensor.
In the conventional rolling bearing device with a sensor, the conventional displacement sensor is one, and the detection surface of the displacement sensor is directed to the outer peripheral surface of the rotating raceway ring. Therefore, there is a problem in that it is possible to find a translational load that vertically acts on the wheel on the basis of a detection value of a displacement sensor, whereas it is impossible to find a moment load in a front-back direction of the vehicle, a moment load in a vertical direction of the vehicle, and a translational load in an axial direction of the wheel, which are generated with a centrifugal force at the time of the turning driving or the like of the vehicle.
Further, the request for improve the sensitivity of the sensor unit to precisely measure the load applied to a rolling bearing exists in the rolling bearing device with a sensor.
Further, in a hub unit, there has conventionally been a request for easily and precisely detecting the translational load in the vertical direction of the vehicle, the translational load in the traveling direction of the vehicle, the translational load in the axial direction of the wheel, the moment load around the vertical direction of the vehicle, and the moment load around the traveling direction of the vehicle.